We propose to purchase a video image intensifier/fluorescent microscope system. The operating principal of image intensification begins with light from a sample striking a photocathode. The electrons emitted by the photocathode are accelerated to high energies while maintaining their spatial registration. This energy is reconverted to light when the electrons strike a phosphor. Image intensification is particularly useful in fluorescence microscopy if the fluorescence emitted by the sample is very low, or the high level of exciting light used for conventional fluorescence bleaches or damages the sample. We will couple this powerful technology to the development of biologically active fluorescent probes to study the following questions: 1) What is the role of solid-like lipid environments in modulating membrane protein functions? 2) What is the mechanism of the antiproliferative effect of heparin? 3) How is uptake and processing of glycosaminoglycans accomplished? 4) What is the relationship of chemotaxis and adhesiveness? 5) Do receptors for chemotactic peptides exist in vivo? 6) Do phagocytosis, receptor mediated endocytosis, and pinocytosis share common membrane microdomains? 7) Is the topology of cell surface receptors altered by different substrates? 8) What is the role of calmodulin and calmodulin binding proteins in secretion? The proposed experiments should increase our knowledge of many fundamental areas of biology, including membrane function, secretion, regulation of cell growth, extracellular matrix functions, and cell motility. These experiments should also provide important information about a wide variety of disease processes, including arteriosclerosis, inflammation, and secretory pathologies such as hyaline membrane disease.